Environmental Protection Agency Narragansett Bay Commission University of Rhode Island Office of Marine Programs

Estuarine Science

Global Environmental Changes: Impacts

The weather and climate of New England has proven to be highly variable over long and short time scales and across short distances. Much of this variability can be attributed to the region's unique geographic location. In a given year, the region can experience hurricanes, blizzards, drought, and more. Over the past century, the historic record indicates that regional temperatures are warming especially in the coastal zone. Clearly, more warming has occurred during winter months. The limited data available indicate that regional snowfall and snowpack have decreased over the past 50 years (although this varies by state and climate zone). Ice-out dates (days in the spring when river ice has melted sufficiently to allow navigation) are occurring from four to six days earlier when compared with 100 years ago. There is limited evidence that extreme weather events may be on the rise, but a more thorough analysis is needed.


How has the regional New England climate warmed over the past century?

New England and New York temperature changes (°F) between 1895 and 1999. The faint lines within the states represent the various climate zones recognized by the National Climate Data Center. (Preparing for a Climate Change, A report of the New England Regional Assessment Group for the US Global Change Research Program).

In an analysis of the historic annual temperature and precipitation records, by region and by state, solid evidence exists that the climate has warmed over the past century (1895-1999). Overall, the region has warmed by 0.7 °F, yet Rhode Island has warmed 2.3 °F. Warming in winter months has been greater than summer-time warming. Regional precipitation has exhibited a modest (4%) increase over the same time period, but as with temperature, the change has not been uniform across the region.



How and what are the scientists predicting about the next century?
Most of what is known about future climates is derived from general circulation models (GCMs) that assess the changing climate. They are the Canadian Global Coupled Model (CGCM) and the Hadley model from the United Kingdom Meteorological Office. Both models project a significant warming (from 6-10 °F) and a moderate to significant increase in precipitation by 2090. It is important to recognize that these models provide "what if" scenarios for us to consider. The predicted temperature increase would be greater than any climate variation experienced by the New England region in the past 10,000 years. If these predicitons are true, the climate of the New England Region would be profoundly different than the climate of today. These changes would occur in a very short time.



What will be the impact of a few degrees temperature increase?
Although a 6-10 °F increase may not seem to be very significant, a comparison of present-day temperatures is instructive. If 6 °F are added to Boston's 30-year average annual temperature (an average of 51.3 °F between 1961- 1990), the resulting temperature is the approximate 30- year annual average for Richmond, VA (57.7 °F). If 10 ° F are added to Boston's 30-year average, the 30-year average for Atlanta, GA (61.3 °F) is the result! An annual average increase of 6-10 °F would have a profound impact on the climate of the region.



Are human activities affecting the climate?
Our understanding influences climate has improved dramatically over the past several decades. There is now strong scientific evidence that much of the global warming experienced in the last half of the 20th century is due to human activities. A large part of the problem is due to the burning of fossil fuels. As these fuels are burned they release gases that build-up in the atmosphere. These gases are called greenhouse gases because they trap heat, radiating it back toward the earth instead of letting it escape into space. Continued build-up of greenhouse gases will lead to additional climate change in the future.




Northern hemisphere temperature changes in the last 1000 years. The yellow marks the range of variability in the data for temperature derived fromproxy sources. (Preparing for a Climate Change, A report of the New England Regional Assessment Group for the US Global Change Research Program).

How have past and present changes impacted the New England region?
Many changes (milder winters, earlier maple sap flows, earlier ice-out dates, reduced snowfall, etc.) are likely a response to a "minor" increase in temperature (0.7 °F for the entire region). The 6-10 °F temperature increases projected for the region must be viewed as serious.



What is one of the more serious regional concerns about climate change?
Stakeholders identified poor air quality as the single most frequent regional concern. Hot, dry summer months are ideal for converting automobile exhaust (NO X ) and volatile organic compounds (VOCs) into ground-level ozone, a major component of SMOG. The same conditions provide the environment for power plant emissions (SO X ) to form sulfate haze. Both SO X and NO X combine with atmospheric water vapor to produce acid clouds and acid rain. If the climate becomes hotter and wetter, and automobile and power plant emissions remain the same or increase, regional air quality and acid rain problems will become worse in the future.



What would future warming trends impact?
Impacts on human health, forests, and sea level from the warming climate are likely to be significant. Both direct health effects such as poor air quality and indirect effects such as warmer winters causing the expansion regions impacted by vector borne diseases such as Lyme disease are concerns. The forests, already under stress, will likely continue to be the most flexible and adaptive. The potential droughts and/or flooding would have profound impacts on regional water quality. Climate change would also affect regional industries such as agriculture, fishing, tourism, and outdoor recreation.



How will warming trends affect estuaries?
Warming coastal waters will experience species shifts and toxic algal blooms. Warmer, wetter winters, coupled with more moisture year-round may lead to flooding, causing a flushing of sewage and other wastes from urban areas into wetlands and coastal marine waters. During the past 30 years we have seen large variations in New England climate. Within this period, the winter water temperature of Narragansett Bay warmed by 3 °C (nearly 6 °F), almost a 1-degree change per decade between 1960 and 1990. Such a dramatic wintertime temperature change has probably altered food chains in temperate coastal waters in southern New England. In the past century, there have been large changes in the abundance of bottom-dwelling "ground fish" in New England, largely attributed to changes in fishing pressure. Warmer winters may have been a contributing factor in the decline of commercially important ground fish in southern New England in recent decades.

As water warms it expands causing sea level to rise. Sea-level rise, which is already occurring, will become a significant problem for low-lying coastal regions (Cape Cod, coastal areas of CT, RI, MA, and NH), affecting both people and coastal wetlands. Currently, the average rate of sea-level rise on the Atlantic coast ranges from 3.5 inches per century in Boston, Massachusetts, to approximately a foot per century in coastal salt marshes in southern Massachusetts.

Different rates of sea-level rise occur at different locations due to local rates of subsidence (settling) or uplift. With the retreat of glacial ice from the region 20,000 years ago, sea coasts began to rebound (or uplift) to a greater or lesser degree from the weight of the ice. The greater the amount of ice removed, the greater the degree of rebound. While portions of the Maine coast may still be rebounding, the coastal areas to the south now appear to be subsiding. About 33 acres of land are lost on Massachusetts' Cape Cod each year- 73% due to advancing seawater and 27% to erosion. A one degree change in ocean temperature would mean a one meter rise in sea level.

The second reason for sea-level rise is the melting of glaciers and ice caps. Clear documentation exists of the recession of approximately 80% of mountain glaciers around the world. There is also limited documentation for a small reduction in the Greenland ice sheet (especially in the southern region).

A last reason for sea-level rise is human activity. As we mine water from aquifers as a source of drinking water, the aquifers recharge more slowly than we empty them, and the mined water finds it's way into the ocean. We also drain wetlands, pumping the water into drainage systems or directly into the oceans. Such direct human activity may account for a third of sea level rise per year. One result of rising sea level is that the saltwater wedge, vital to the health of an estuary, would migrate upstream, causing a shift of marine ecosystems upriver unless freshwater runoff is increased.

Sea-level rise will cause salt water to move into new areas. This is called saltwater intrusion and it could convert some areas of coastal freshwater wetlands to salt marshes. Groundwater could also be affected, as brackish water infiltrates aquifers that supply drinking water to coastal communities. Saltwater intrusion combined with low freshwater flow, could result in a higher chloride water content in important aquifer systems and water supplies. Low flow, a rise in sea level, or both could affect the water supplies in coastal regions. In addition, as sea level continues to rise, the amount of the region's coastal area subject to flooding from coastal storms will increase, especially in areas of low relief. Increases in sea level can cause dramatic changes, as higher sea levels would provide a raised base from which storm surges may sweep inland, allowing for greater and more widespread damage than would occur with lower sea levels. Even if storm strength were not increased, higher sea levels will result in more damage.



How will the economy be impacted?
A limited assessment of the economic impact of climate change was conducted on natural resources, tourism, and health care industries. The major conclusion from this intitial economic analysis is that the impacts of climate change will vary and be significant. The economic impacts will likely be greatest on the Human Health sector, moderate on tourism and least severe on the Natural Resource Sector. This initial economic assessment has identified the need for a more extensive analysis.

The fishing industry will be affected. Scientists suggest that warmer late winter-early spring temperatures combined with continued sea-level rise could have a significant impact for commercial fishing. The greatest portion of U.S. commercial fishery catches (except Alaska) are estuarine dependent, with 32% of the fisheries of Cape Cod and north estuarine dependent. Coastal wetlands, estuaries, and other intertidal areas such as mud flats are important nursery grounds for many species of commercial fish and shellfish and important feeding grounds for many migrating waterfowl. Because these ecosystems often are adapted to specific temperature, salinity, and tidal conditions, commercial species and whole ecosystems could be lost if the upstream conditions are not suitable for migration or the species are unable to migrate in response to changing sea level. A sea-level rise that is rapid enough to damage coastal wetlands would cause a significant decline in coastal fisheries.

Shoreline construction which prevents erosion or submergence or is otherwise unsuitable would prevent estuarine and intertidal habitat shifts that might have occurred due to sea-level rise. Preserving estuarine and intertidal habitats will become more of a significant concern, as the future climate changes.

The winter flounder case study conducted by the US Global Change Research Program addresses the issue of current climate change impacts on abundance of this commercially important marine species. The winter flounder may well be an indicator species sensitive to increases in water temperatures. Warmer water temperatures appear to have set off a chain of circumstances that began with the loss of the winter flounder population and resulted in increased populations of warmer water invertebrates and migrant fishes.

Another industry sure to be affected is the insurance industry. Evidence of increases in extreme weather events is provided in the form of increasing trends in weather-related insurance claims. Complicating the increase in severe storms is the fact that human population in the US is increasing, and more people are building more expensive homes in weather-sensitive areas (coastal property susceptible to hurricanes, and floodplains vulnerable to flooding).





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